The present invention relates to a laser beam detecting device for a construction machine wherein a beam sensor is mounted above a leveling implement, a laser beam for forming a reference plane is detected by the beam sensor, and information based on the detection of the laser beam is displayed on a display.
In a civil engineering work such as a land formation work for leveling land there is used a construction machine equipped with a leveling implement, such as a shovel car, a bulldozer, or a crawler.
Formerly, an operator of a construction machine executed a land formation work with his eye while making a survey repeatedly to check the degree of flatness.
Recently, however, with use of a rotating laser, it has become possible for an operator of a construction machine to check the degree of flatness directly on an operator seat. In this case, a laser beam as a reference is detected by a beam sensor mounted above a leveling implement and an offset direction from the reference laser beam is displayed on a display.
The beam sensor is mounted at a relatively high position above the leveling implement to prevent the laser beam from being intercepted by an arm or any other component installed in the body of the construction machine.
As to a laser beam detecting range in the beam sensor, only one reference position has heretofore been set centrally of the sensor.
Since the detection range for the incidence of laser beam in the beam sensor is thus limited, if a laser beam incidence position is outside the detection range, there will be made no display as to in which direction the laser beam should travel.
Particularly, in a banking or trenching work, the leveling implement shifts largely in the vertical direction, so there occurs a case where the detection range of the beam sensor becomes deficient.
For example, in a trenching work with use of an excavator (a shovel car), a bucket is moved over a relatively wide range in the earth surface direction (vertical direction) from a to-be-trenched depth, so that a wider detection range is desired.
On the other hand, if there is adopted a structure having a wider detectable range of the beam sensor, a beam receiving portion in the laser beam detecting device concerned becomes larger (i.e., longer in the vertical direction) physically, resulting in that when the detecting device is to be attached, for example, to an arm of a construction machine, it is difficult to do so. Additionally, there arises a danger that the detecting device may interfere with any other portion (e.g. the leveling implement or earth).
It is an object of the present invention to provide a laser beam detecting device for a construction machine capable of detecting a laser beam in a wider detection range without enlarging a beam receiving portion.
The object of the present invention is achieved by a laser beam detecting device for a construction machine described herein.
In a laser beam detecting device for a construction machine according to a preferred mode of the present invention, a beam sensor is mounted above a leveling implement, a laser beam as a reference is detected by the beam sensor, and information based on the beam detection is displayed on a display.
A plurality of reference positions are established in a detection range of a beam receiving portion of the beam sensor and one of the reference positions is made a standard position, while the other reference positions are made offset positions. First and second offset positions are established respectively above and below the standard position. There is provided a display (display portion) indicating in which of standard and offset positions the laser beam detection is being conducted.
In the beam sensor used in the laser beam detecting device according to the present invention, the reference positions (height indications) are capable of being offset, whereby height information in a predetermined direction can be detected and displayed in a wider range. Preferably, a laser beam is detected, and on the basis of the detected beam incidence position, the direction in which the leveling implement is to be moved, as well as the distance at which the leveling implement is to be moved, are indicated to the operator.
The laser beam detecting device is fixed to a predetermined position of, for example, an arm of a construction machine such as an excavator through a magnet or a clamp. The predetermined position as referred to herein indicates a position which permits an offset to be clarified between a tip end of a leveling implement such as a bucket which forms a working surface and the predetermined position.
For example, in the case where there are three reference positions, it is preferable that a central reference position be made a standard position, that offset positions be established one each above and below the standard position, and that position information, which urges movement, be indicated to the operator in the same quantity in the vertical direction. Since not only the central reference position (on-grade position) alone in the laser beam detection range of the laser beam detecting device, but also upper and lower offset positions with respect to the central reference position can be established, it is possible to substantially expand the detection range in the predetermined direction.
The detection range in the predetermined direction can be widened according to contents of a work to be executed without changing the size of the laser beam receiving portion in the beam sensor, and therefore the work can be carried out in a more accurate manner.
Thus, according to the present invention, reference positions can be offset with respect to the predetermined direction without any change in the detection range.
For example, although the detection range on one side becomes narrow, this poses no problem in view of the contents of a work which involves establishing offset positions. For example, in case of a trenching work, it is only when trenching proceeds to excess downward beyond a to-be-trenched depth that the detection range shifts, and therefore even if the detection range lower than the to-be-trenched depth is narrow, it will do.
The laser beam detecting device is attached, at the back of its body, to a predetermined position (e.g., arm) of a construction machine removably with screws or the like.
Alternatively, the laser beam detecting device may be fixed magnetically to a leveling implement of a construction machine. In this case, a strong magnetic force can be obtained by holding plural magnets in between plural net plates. In this case there is attained a high durability because the steel plates are in contact with the leveling implement. Besides, since the steel plates are each adapted to move slightly, they can fix the magnets securely and prevent them from coming off even if the magnet surfaces are somewhat uneven or even under an abrupt shock.
The laser beam detecting device may also be fixed to a pole or the like which is fixed to the leveling implement. In this case, a clamp is often used for the fixing.